How to check GST or sales tax on an invoice
GST and sales tax work like VAT: a percentage added to the price. To check one:
- Taxable amount. Add the line totals and subtract any discount.
- Tax. Multiply the taxable amount by the rate. It should equal the tax printed on the invoice, within a cent of rounding.
- Total. Taxable amount plus tax plus shipping should equal the amount due.
Worked example at Australia's 10% GST:
| Line | Amount |
|---|---|
| 5 × 40.00 | 200.00 |
| Discount | −20.00 |
| Taxable amount | 180.00 |
| GST at 10% | 18.00 |
| Total due | 198.00 |
If the invoice shows GST of 20.00 or a total of 200.00, the checker reports the difference with the page it came from.
Typical rates by country
Pick a country above and its usual rates appear as buttons. You can always type a different rate.
| Country | Tax | Typical rates |
|---|---|---|
| Australia | GST | 10%, GST-free 0% |
| New Zealand | GST | 15%, zero-rated 0% |
| Singapore | GST | 9%, zero-rated 0% |
| India | GST | 5%, 18%, 40%, nil |
| Canada | GST/HST | 5% GST; HST 13% (Ontario), 14% (Nova Scotia), 15% (NB, NL, PEI) |
| United States | Sales tax | Varies by state and locality |
Rates were last checked on 9 October 2026. They are a convenience, not tax advice, and the correct rate depends on what is sold and where. Confirm with your tax authority or accountant.
Common GST and sales tax mistakes
- Tax on the wrong base. GST charged on the price before a discount.
- Wrong rate. A standard rate applied to GST-free goods, or an old rate left in a template.
- Split rates that do not add up. CGST and SGST halves, or HST components, that do not total the rate you expected.
- Tax on an exempt or zero-rated supply. Tick "No tax should apply" and the checker warns if the invoice charges any.
- Totals that do not add up. A final amount that differs from the parts.
What this checker does not do
It checks that the invoice is consistent with itself and with the rate you chose. It does not decide which rate is legally correct, verify a GST or tax registration number against a government register, or confirm the supplier is genuine. For UK and EU invoices use the VAT invoice checker. To see every check we run, read about invoice validation, and for the arithmetic see the invoice calculation checker.